Some conventional 3D CAD browsing tools display a CAD object as a virtual object on a display such as a CRT or on the display unit of an HMD in combination with the VR technology.
In recent years, studies about mixed reality (to be referred to as “MR” hereinafter) which aims at seamless combination of the physical space and virtual space have extensively been done. MR aims at coexistence of the physical space and the virtual reality (to be referred to as VR hereinafter) world which can conventionally be experienced only in a situation isolated from the physical space and provides MR by combining an image in the physical space with an image in the virtual space (e.g., Japanese Patent Laid-Open No. 11-136706).
In the former case, since the sense of actual size is absent, it is difficult to grasp the size of a designed object. In addition, since a pointing device such as a mouse is used to observe a target CAD object from various directions, complex and time-consuming operations are necessary to change the position and orientation of the object and the viewpoint and line of sight of the observer.
In the latter case as well, since comparison to an object which exists in the physical world is impossible, the size and the like of a designed object are hard to grasp.
Generally, to browse 3D CAD data, many operations are required to observe an object from various directions, select some parts, or set the non-display mode. In the latter system, however, it is difficult to mount a complex user interface because the program is based on cumbersome 3D CG.